The disclosure relates to durable and/or scratch-resistant coating materials and articles including the same, and more particularly to coating materials exhibiting high hardness and a wide optical band gap, and articles including the same.
Transparent substrates are often used in displays in consumer electronic devices such as smart phones and tablets. Other applications are also possible, such as architectural, automotive, appliances and the like. For such uses, the substrate should be abrasion resistant, scratch resistant, and should provide acceptable optical transparency and color point (in transmittance and/or reflectance). In addition, when used in displays, the substrate should minimize light absorption to minimize energy use, thus prolonging the battery life in portable device. The substrate should also exhibit minimum light reflectance so the display is readable in bright, ambient light. Moreover, the transmittance and reflectance should also be optimized so that colors in the display are accurately rendered over a range of viewing angles.
The application of hard coating(s) onto the surface of substrate has been attempted to enhance at least one or more of these desirable properties. Such coatings may be formed using physical vapor deposition (PVD) processes and can include aluminum-based materials such as aluminum nitride, aluminum oxynitride, and silicon aluminum oxynitride. Such materials exhibit high hardness, and optical transparency and colorlessness; however there may be processing limitations associated with such materials.
Known sputtered or PVD-formed silicon-based materials include a hydrogen-free SiNx, which may exhibit a hardness of about 22 gigaPascals (GPa) at stoichiometric N/Si=1.33. Known RF sputtered SiNx films have shown about 93% density and a hardness of about 25 GPa. It should be noted that such sputtered silicon-based materials require long deposition times. Moreover, such materials include less than about 1 atomic % hydrogen and exhibit inferior optical properties.
A recognized alternative is forming durable and/or scratch resistant materials by chemical vapor deposition (CVD), which includes plasma enhanced chemical vapor deposition (PECVD). Accordingly, there is a need for providing durable and/or scratch resistant coating materials that may be formed by a variety of methods including CVD and PECVD methods, and which exhibit high hardness, optical transparency and colorlessness.